Method for transmitting a uplink signal based on a codebook in a wireless communication system and apparatus therefor

ABSTRACT

This specification provides a method of transmitting an uplink signal based on a codebook in a wireless communication system. More specifically, the method performed by a UE includes receiving, from a base station, downlink control information (DCI) including a first transmit precoding matrix indicator (TPMI), determining a codebook subset related to the transmission of the uplink signal based on the first TPMI, and transmitting, to the base station, the uplink signal based on the determined codebook subset. Accordingly, there is an advantage in that flexibility in the transmission antenna design of a UE can be increased because the degree of freedom of antenna port selection is increased.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Provisional Application No.62/555,607 filed Sep. 7, 2017 and No. 62/566,568 filed on Oct. 2, 2017in US, the entire contents of which is hereby incorporated by referencein its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

This specification relates to a wireless communication system and, moreparticularly, to a method of transmitting an uplink signal based on acodebook and an apparatus supporting the same.

Related Art

Mobile communication systems have been generally developed to providevoice services while guaranteeing user mobility. Such mobilecommunication systems have gradually expanded their coverage from voiceservices through data services up to high-speed data services. However,as current mobile communication systems suffer resource shortages andusers demand even higher-speed services, development of more advancedmobile communication systems is needed.

The requirements of the next-generation mobile communication system mayinclude supporting huge data traffic, a remarkable increase in thetransfer rate of each user, the accommodation of a significantlyincreased number of connection devices, very low end-to-end latency, andhigh energy efficiency. To this end, various techniques, such as smallcell enhancement, dual connectivity, massive multiple input multipleoutput (MIMO), in-band full duplex, non-orthogonal multiple access(NOMA), supporting super-wide band, and device networking, have beenresearched.

SUMMARY OF THE INVENTION

This specification provides a method of configuring a codebook for aspecific number of port selections.

Technical objects to be achieved in the present invention are notlimited to the aforementioned technical objects, and other technicalobjects not described above may be evidently understood by a personhaving ordinary skill in the art to which the present invention pertainsfrom the following description.

This specification provides a method of transmitting an uplink signalbased on a codebook in a wireless communication system.

Specifically, the method performed by a UE includes receiving, from abase station, downlink control information (DCI) including a firsttransmit precoding matrix indicator (TPMI), determining a codebooksubset related to the transmission of the uplink signal based on thefirst TPMI, and transmitting, to the base station, the uplink signalbased on the determined codebook subset. The codebook subset is includedin a codebook for a rank 1 using four antenna ports, and the codebooksubset includes at least one codeword for selecting one antenna port.

Furthermore, in this specification, the at least one codeword is

${\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\0\end{bmatrix}},{\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\0\end{bmatrix}},{{\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\0\end{bmatrix}}\mspace{14mu} {and}\mspace{14mu} {{\frac{1}{2}\begin{bmatrix}0 \\0 \\0 \\1\end{bmatrix}}.}}$

Furthermore, in this specification, the codebook for a rank 1 using theone antenna ports includes a codebook based on discrete Fouriertransform spread orthogonal frequency division multiplexing(DFT-s-OFDM).

Furthermore, in this specification, the DCI further includes a secondTPMI related to port combining of an antenna port selected based on thefirst TPMI.

Furthermore, in this specification, the size of the second TPMI isdetermined based on the size of the first TPMI.

Furthermore, in this specification, the first TPMI is represented as anX-bitmap, and a value of the X is the number of antenna ports.

Furthermore, in this specification, the first TPMI includes a widebandTPMI.

Furthermore, in this specification, the method further includesreceiving, from the base station, a signaling including a power scalingfactor to be applied to the at least one codeword and applying the powerscaling factor to the at least one codeword.

Furthermore, in this specification, the power scaling factor isconfigured by considering the capability of the UE.

Furthermore, this specification, a user equipment (UE) transmitting auplink signal based on a codebook in a wireless communication systemincludes a radio frequency (RF) module configured to transmit andreceive radio signals and a processor functionally connected to the RFmodule. The processor is configured to receive, from a base station,downlink control information (DCI) including a first transmit precodingmatrix indicator (TPMI), determine a codebook subset related to thetransmission of the uplink signal based on the first TPMI, and transmit,to the base station, the uplink signal based on the determined codebooksubset. The codebook subset is included in a codebook for a rank 1 usingfour antenna ports, and the codebook subset includes at least onecodeword for selecting one antenna port.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings included as part of the detailed descriptionin order to help understanding of the present invention provideembodiments of the present invention, and describe the technicalcharacteristics of the present invention along with the detaileddescription.

FIG. 1 is a diagram showing an example of an overall system structure ofNR to which a method proposed in this specification may be applied.

FIG. 2 shows a relation between an uplink frame and a downlink frame ina wireless communication system to which a method proposed in thisspecification may be applied.

FIG. 3 shows an example of a resource grid supported in a wirelesscommunication system to which a method proposed in this specificationmay be applied.

FIG. 4 shows an example of a self-contained sub-frame structure to whicha method proposed in this specification may be applied.

FIG. 5 illustrates a transceiver unit model in a wireless communicationsystem to which the present invention may be applied.

FIG. 6 is a diagram showing a hybrid beamforming structure in a TXRU andphysical antenna viewpoint in a wireless communication system to whichthe present invention may be applied.

FIG. 7 is a diagram showing an example of a beam sweeping operation towhich a method proposed in this specification may be applied.

FIG. 8 is a diagram showing an example of an antenna array to which amethod proposed in this specification may be applied.

FIG. 9 is a flowchart showing an example of an operating method of a UEperforming codebook-based uplink transmission, which is proposed in thisspecification.

FIG. 10 illustrates a block diagram of a wireless communicationapparatus to which the methods proposed in this specification may beapplied.

FIG. 11 illustrates a block diagram of a communication apparatusaccording to an embodiment of the present invention.

FIG. 12 is a diagram showing an example of the RF module of the wirelesscommunication apparatus to which a method proposed in this specificationmay be applied.

FIG. 13 is a diagram showing another example of the RF module of thewireless communication apparatus to which a method proposed in thisspecification may be applied.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Some embodiments of the present disclosure are described in detail withreference to the accompanying drawings. A detailed description to bedisclosed along with the accompanying drawings is intended to describesome exemplary embodiments of the present disclosure and is not intendedto describe a sole embodiment of the present disclosure. The followingdetailed description includes more details in order to provide fullunderstanding of the present disclosure. However, those skilled in theart will understand that the present disclosure may be implementedwithout such more details.

In some cases, in order to avoid making the concept of the presentdisclosure vague, known structures and devices are omitted or may beshown in a block diagram form based on the core functions of eachstructure and device.

In the present disclosure, a base station has the meaning of a terminalnode of a network over which the base station directly communicates witha terminal. In this document, a specific operation that is described tobe performed by a base station may be performed by an upper node of thebase station according to circumstances. That is, it is evident that ina network including a plurality of network nodes including a basestation, various operations performed for communication with a terminalmay be performed by the base station or other network nodes other thanthe base station. The base station (BS) may be substituted with anotherterm, such as a fixed station, a Node B, an eNB (evolved-NodeB), a basetransceiver system (BTS), or an access point (AP). Furthermore, theterminal may be fixed or may have mobility and may be substituted withanother term, such as user equipment (UE), a mobile station (MS), a userterminal (UT), a mobile subscriber station (MSS), a subscriber station(SS), an advanced mobile station (AMS), a wireless terminal (WT), amachine-type communication (MTC) device, a machine-to-Machine (M2M)device, or a device-to-device (D2D) device.

Hereinafter, downlink (DL) means communication from a base station toUE, and uplink (UL) means communication from UE to a base station. InDL, a transmitter may be part of a base station, and a receiver may bepart of UE. In UL, a transmitter may be part of UE, and a receiver maybe part of a base station.

Specific terms used in the following description have been provided tohelp understanding of the present disclosure, and the use of suchspecific terms may be changed in various forms without departing fromthe technical sprit of the present disclosure.

The following technologies may be used in a variety of wirelesscommunication systems, such as code division multiple access (CDMA),frequency division multiple access (FDMA), time division multiple access(TDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), and non-orthogonalmultiple access (NOMA). CDMA may be implemented using a radiotechnology, such as universal terrestrial radio access (UTRA) orCDMA2000. TDMA may be implemented using a radio technology, such asglobal system for mobile communications (GSM)/general packet radioservice (GPRS)/enhanced data rates for GSM evolution (EDGE). OFDMA maybe implemented using a radio technology, such as Institute of electricaland electronics engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX),IEEE 802.20, or evolved UTRA (E-UTRA). UTRA is part of a universalmobile telecommunications system (UMTS). 3rd generation partnershipproject (3GPP) Long term evolution (LTE) is part of an evolved UMTS(E-UMTS) using evolved UMTS terrestrial radio access (E-UTRA), and itadopts OFDMA in downlink and adopts SC-FDMA in uplink. LTE-advanced(LTE-A) is the evolution of 3GPP LTE.

Embodiments of the present disclosure may be supported by the standarddocuments disclosed in at least one of IEEE 802, 3GPP, and 3GPP2, thatis, radio access systems. That is, steps or portions that belong to theembodiments of the present disclosure and that are not described inorder to clearly expose the technical spirit of the present disclosuremay be supported by the documents. Furthermore, all terms disclosed inthis document may be described by the standard documents.

In order to more clarify a description, 3GPP LTE/LTE-A is chieflydescribed, but the technical characteristics of the present disclosureare not limited thereto.

Definition of Terms

eLTE eNB: An eLTE eNB is an evolution of an eNB that supports aconnection for an EPC and an NGC.

gNB: A node for supporting NR in addition to a connection with an NGC.

New RAN: A radio access network that supports NR or E-UTRA or interactswith an NGC.

Network slice: A network slice is a network defined by an operator so asto provide a solution optimized for a specific market scenario thatrequires a specific requirement together with an inter-terminal range.

Network function: A network function is a logical node in a networkinfra that has a well-defined external interface and a well-definedfunctional operation.

NG-C: A control plane interface used for NG2 reference point between newRAN and an NGC.

NG-U: A user plane interface used for NG3 reference point between newRAN and an NGC.

Non-standalone NR: A deployment configuration in which a gNB requires anLTE eNB as an anchor for a control plane connection to an EPC orrequires an eLTE eNB as an anchor for a control plane connection to anNGC.

Non-standalone E-UTRA: A deployment configuration an eLTE eNB requires agNB as an anchor for a control plane connection to an NGC.

User plane gateway: A terminal point of NG-U interface.

General System

FIG. 1 is a diagram illustrating an example of an overall structure of anew radio (NR) system to which a method proposed by the presentdisclosure may be implemented.

Referring to FIG. 1, an NG-RAN is composed of gNBs that provide an NG-RAuser plane (new AS sublayer/PDCP/RLC/MAC/PHY) and a control plane (RRC)protocol terminal for a UE.

The gNBs are connected to each other via an Xn interface.

The gNBs are also connected to an NGC via an NG interface.

More specifically, the gNBs are connected to a Access and MobilityManagement Function (AMF) via an N2 interface and a User Plane Function(UPF) via an N3 interface.

New Rat (NR) Numerology and Frame Structure

In the NR system, multiple numerologies may be supported. Thenumerologies may be defined by subcarrier spacing and cyclic prefix (CP)overhead. Spacing between the plurality of subcarriers may be derived byscaling basic subcarrier spacing into an integer N (or μ ). In addition,although a very low subcarrier spacing is assumed not to be used at avery high subcarrier frequency, a numerology to be used may be selectedindependent of a frequency band.

In addition, in the NR system, a variety of frame structures accordingto the multiple numerologies may be supported.

Hereinafter, an Orthogonal Frequency Division Multiplexing (OFDM)numerology and a frame structure, which may be considered in the NRsystem, will be described.

A plurality of OFDM numerologies supported in the NR system may bedefined as in Table 1.

TABLE 1 μ Δf = 2^(μ) · 15 [kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120 Normal 4 240 Normal 5 480 Normal

Regarding a frame structure in the NR system, a size of various fieldsin the time domain is expressed as a multiple of a time unit ofT_(s)=1/(Δƒ_(max)·N_(f)) . In this case, Δƒ_(max)=480·10³, andN_(f)=4096. DL and UL transmission is configured as a radio frame havinga section of T_(f)=(Δƒ_(max)N_(f)/100)·T_(s)=10 ms. The radio frame iscomposed of ten subframes each having a section ofT_(sf)=(Δƒ_(max)N_(f)/1000)·T_(s)=1 ms. In this case, there may be a setof UL frames and a set of DL frames.

FIG. 2 illustrates a relationship between a UL frame and a DL frame in awireless communication system to which a method proposed by the presentdisclosure may be implemented.

As illustrated in FIG. 2, a UL frame number I from a user equipment (UE)needs to be transmitted T_(TA)=N_(TA)T_(s) before the start of acorresponding DL frame in the UE.

Regarding the numerology μ, slots are numbered in ascending order ofn_(s) ^(μ)∈{0, . . . ,N_(subframe) ^(slots,μ)−1 }in a subframe, and inascending order of n_(s,f) ^(μ)∈{0, . . . ,N_(subframe) ^(slots,μ)−1 }ina radio frame. One slot is composed of continuous OFDM symbols ofN_(symb) ^(μ), and N_(symb) ^(μ) is determined depending on a numerologyin use and slot configuration. The start of slots n_(s) ^(μ) in asubframe is temporally aligned with the start of OFDM symbols n_(s)^(μN) _(symb) ^(μ) in the same subframe.

Not all UEs are able to transmit and receive at the same time, and thismeans that not all OFDM symbols in a DL slot or an UL slot are availableto be used.

Table 2 shows the number of OFDM symbols per slot for a normal CP in thenumerology μ, and Table 3 shows the number of OFDM symbols per slot foran extended CP in the numerology μ.

TABLE 2 Slot configuration 0 1 μ N_(symb) ^(μ) N_(frame) ^(slots,μ)N_(subframe) ^(slots,μ) N_(symb) ^(μ) N_(frame) ^(slots,μ) N_(subframe)^(slots,μ) 0 14 10 1 7 20 2 1 14 20 2 7 40 4 2 14 40 4 7 80 8 3 14 80 8— — — 4 14 160 16 — — — 5 14 320 32 — — —

TABLE 3 Slot configuration 0 1 μ N_(symb) ^(μ) N_(frame) ^(slots,μ)N_(subframe) ^(slots,μ) N_(symb) ^(μ) N_(frame) ^(slots,μ) N_(subframe)^(slots,μ) 0 12 10 1 6 20 2 1 12 20 2 6 40 4 2 12 40 4 6 80 8 3 12 80 8— — — 4 12 160 16 — — — 5 12 320 32 — — —

NR Physical Resource

Regarding physical resources in the NR system, an antenna port, aresource grid, a resource element, a resource block, a carrier part,etc. may be considered.

Hereinafter, the above physical resources possible to be considered inthe NR system will be described in more detail.

First, regarding an antenna port, the antenna port is defined such thata channel over which a symbol on one antenna port is transmitted can beinferred from another channel over which a symbol on the same antennaport is transmitted. When large-scale properties of a channel receivedover which a symbol on one antenna port can be inferred from anotherchannel over which a symbol on another antenna port is transmitted, thetwo antenna ports may be in a QC/QCL (quasi co-located or quasico-location) relationship. Herein, the large-scale properties mayinclude at least one of delay spread, Doppler spread, Doppler shift,average gain, and average delay.

FIG. 3 illustrates an example of a resource grid supported in a wirelesscommunication system to which a method proposed by the presentdisclosure may be implemented.

Referring to FIG. 3, a resource grid is composed of N_(RB) ^(μ)N_(sc)^(RB) subcarriers in a frequency domain, each subframe composed of 14·2μOFDM symbols, but the present disclosure is not limited thereto.

In the NR system, a transmitted signal is described by one or moreresource grids, composed of N_(RB) ^(μ)N_(sc) ^(RB) subcarriers, and2^(μ)N_(symb) ^((μ)) OFDM symbols Herein, N_(RB) ^(μ)≤N_(RB) ^(max,μ).The above N_(RB) ^(max,μ) indicates the maximum transmission bandwidth,and it may change not just between numerologies, but between UL and DL.

In this case, as illustrated in FIG. 3, one resource grid may beconfigured for the numerology μ and an antenna port p.

Each element of the resource grid for the numerology μ and the antennaport p is indicated as a resource element, and may be uniquelyidentified by an index pair (k,l). Herein, k=0, . . . ,N_(RB) ^(μ)N_(sc)^(RB)−1 is an index in the frequency domain, and l=0, . . .,2^(μ)N_(symb) ^((μ))−1 indicates a location of a symbol in a subframe.To indicate a resource element in a slot, the index pair (k,l) is used.Herein, l=0, . . . ,N_(symb) ^(μ)−1.

The resource element (k,l) for the numerology μ and the antenna port pcorresponds to a complex value a_(k,l) ^((p)). When there is no risk ofconfusion or when a specific antenna port or numerology is specified,the indexes p and μ may be dropped and thereby the complex value maybecome a_(kl) ^((p)) or a_(k,l.)

In addition, a physical resource block is defined as N_(sc) ^(RB)=12continuous subcarriers in the frequency domain. In the frequency domain,physical resource blocks may be numbered from 0 to N_(RB) ^(μ)=1. Atthis point, a relationship between the physical resource block numbern_(PRB) and the resource elements (k,l) may be given as in Equation 1.

$\begin{matrix}{n_{PRB} = \lfloor \frac{k}{N_{sc}^{RB}} \rfloor} & \lbrack {{Equation}\mspace{14mu} 1} \rbrack\end{matrix}$

In addition, regarding a carrier part, a UE may be configured to receiveor transmit the carrier part using only a subset of a resource grid. Atthis point, a set of resource blocks which the UE is configured toreceive or transmit are numbered from 0 to N_(URB) ^(μ)−1 in thefrequency region.

Self-Contained Subframe Structure

FIG. 4 is a diagram illustrating an example of a self-contained subframestructure in a wireless communication system to which the presentdisclosure may be implemented.

In order to minimize data transmission latency in a TDD system, 5G newRAT considers a self-contained subframe structure as shown in FIG. 4.

In FIG. 4, a diagonal line area (symbol index 0) represents a UL controlarea, and a black area (symbol index 13) represents a UL control area. Anon-shade area may be used for DL data transmission or for UL datatransmission. This structure is characterized in that DL transmissionand UL transmission are performed sequentially in one subframe andtherefore transmission of DL data and reception of UL ACK/NACK may beperformed in the subframe. In conclusion, it is possible to reduce timefor retransmitting data upon occurrence of a data transmission error andthereby minimize a latency of final data transmission.

In this self-contained subframe structure, a time gap is necessary for abase station or a UE to switch from a transmission mode to a receptionmode or to switch from the reception mode to the transmission mode. Tothis end, some OFDM symbols at a point in time of switching from DL toUL in the self-contained subframe structure are configured as a guardperiod (GP).

Analog Beamforming

Since a wavelength is short in a Millimeter Wave (mmW) range, aplurality of antenna elements may be installed in the same size of area.That is, a wavelength in the frequency band 30 GHz is 1 cm, and thus, 64(8×8) antenna elements may be installed in two-dimensional arrangementwith a 0.5 lambda (that is, a wavelength) in 4×4 (4 by 4) cm panel.Therefore, in the mmW range, the coverage may be enhanced or athroughput may be increased by increasing a beamforming (BF) gain with aplurality of antenna elements.

In this case, in order to enable adjusting transmission power and phasefor each antenna element, if a transceiver unit (TXRU) is included,independent beamforming for each frequency resource is possible.However, it is not cost-efficient to install TXRU at each of about 100antenna elements. Thus, a method is considered in which a plurality ofantenna elements is mapped to one TXRU and a direction of beam isadjusted with an analog phase shifter. Such an analog BF method is ableto make only one beam direction over the entire frequency band, andthere is a disadvantage that frequency-selective BF is not allowed.

Hybrid BF may be considered, which is an intermediate between digital BFand analog BF and has the number of TXRUs B less than the number ofantenna elements Q. In this case, although varying depending upon amethod of connecting the number of TXRU B and the number of antennaelements Q, beam directions capable of being transmitted at the sametime are restricted to be less than B.

Hereinafter, typical examples of a method of connecting TXRUs andantenna elements will be described with reference to drawings.

FIG. 5 is an example of a transceiver unit model in a wirelesscommunication system to which the present disclosure may be implemented.

A TXRU virtualization model represents a relationship between outputsignals from TXRUs and output signals from antenna elements. Dependingon a relationship between antenna elements and TXRUs, the TXRUvirtualization model may be classified as a TXRU virtualization modeloption-1: sub-array partition model, as shown in FIG. 5(a), or as a TXRUvirtualization model option-2: full-connection model.

Referring to FIG. 5(a), in the sub-array partition model, the antennaelements are divided into multiple antenna element groups, and each TXRUmay be connected to one of the multiple antenna element groups. In thiscase, the antenna elements are connected to only one TXRU.

Referring to FIG. 5(b), in the full-connection model, signals frommultiple TXRUs are combined and transmitted to a single antenna element(or arrangement of antenna elements). That is, this shows a method inwhich a TXRU is connected to all antenna elements. In this case, theantenna elements are connected to all the TXRUs.

In FIG. 5, q represents a transmitted signal vector of antenna elementshaving M number of co-polarized in one column. W represents a widebandTXRU virtualization weight vector, and W represents a phase vector to bemultiplied by an analog phase shifter. That is, a direction of analogbeamforming is decided by W. x represents a signal vector of M_TXRUnumber of TXRUs.

Herein, mapping of the antenna ports and TXRUs may be performed on thebasis of 1-to-1 or 1-to-many.

TXRU-to-element mapping In FIG. 5 is merely an example, and the presentdisclosure is not limited thereto and may be equivalently applied evento mapping of TXRUs and antenna elements which can be implemented in avariety of hardware forms.

Furthermore, in the new RAT system, if multiple antennas are used, ahybrid beamforming scheme in which digital beamforming and analogbeamforming have been combined is emerging.

In this case, the analog beamforming (or radio frequency (RF)beamforming) means an operation for an RF stage to perform precoding (orcombining). In the hybrid beamforming, each of a baseband stage and anRF stage performs precoding (or combining). Accordingly, there areadvantages in that the number of RF chains and the number of digital(D)/analog (A) (or A/D) converters are reduced and performance closer tothat of digital beamforming can be achieved.

For convenience sake, a hybrid beamforming structure may be expressed asN transceiver units (TXRU) and M physical antennas. In this case,digital beamforming for L data layers to be transmitted by atransmission stage may be expressed as an N by L matrix. Thereafter,converted N digital signals are converted into an analog signal via theTXRU, and analog beamforming expressed in an M by N matrix is thenapplied to the analog signal.

FIG. 6 is a diagram showing a hybrid beamforming structure in the TXRUand physical antenna viewpoint in a wireless communication system towhich the present invention may be applied.

FIG. 6 illustrates a case where the number of digital beams is L and thenumber of analog beams is N.

The new RAT system is designed so that a base station can change analogbeamforming in units of symbol in order to support more efficientbeamforming for a UE positioned in a specific area. Furthermore, whenspecific N TXRUs and M RF antennas are defined as one antenna panel inFIG. 6, a method of introducing a plurality of antenna panels to whichindependent hybrid beamforming can be applied is taken intoconsideration in the new RAT system.

Channel State Information (CSI) Feedback

In the 3GPP LTE/LTE-A system, a user equipment (UE) has been defined toreport channel state information (CSI) to a base station (BS or eNB).

CSI collectives indicates information capable of indicating quality of aradio channel (or also called a link) formed between a UE and an antennaport. For example, a rank indicator (RI), a precoding matrix indicator(PMI) or a channel quality indicator (CQI) corresponds to CSI.

In this case, the RI indicates rank information of a channel and meansthe number of streams received by a UE through the same time-frequencyresource. This value is determined depending on the long term fading ofa channel, so the RI has a longer period than a PMI or CQI and is fedback from a UE to a BS. The PMI is a value into which a channel spacecharacteristic has been incorporated, and indicates a precoding indexpreferred by a UE based on metric, such as asignal-to-interference-plus-noise ratio (SINR). The CQI is a valueindicative of the intensity of a channel and means a received SINR thatmay be obtained when a BS uses a PMI.

In the 3GPP LTE/LTE-A system, a BS configures multiple CSI processes fora UE and may receive CSI reporting for each process. In this case, theCSI process includes a CSI-RS for signal quality measurement from a BSand a CSI-interference measurement (CSI-IM) resource for interferencemeasurement.

Reference Signal (RS) Virtualization

In mmW, a PDSCH may be transmitted in one analog beam direction only atone occasion through analog beamforming. In this case, data transmissionmay be possible from a BS to only some UEs in the correspondingdirection. Accordingly, data transmission may be performed on multipleUEs in several analog beam directions at the same time by differentlyconfiguring the analog beam directions on an antenna port basis, ifnecessary.

FIG. 7 is a diagram showing an example of a beam sweeping operation towhich a method proposed in this specification may be applied.

If a BS uses a plurality of analog beams as described above in FIG. 6,an analog beam advantageous for signal reception may be different foreach UE. Accordingly, a beam sweeping operation for all of UEs to havereception opportunities by changing a plurality of analog beams to beapplied by a BS based on a symbol in a specific sub-frame with respectto at least a synchronization signal, system information, and paging istaken into consideration.

FIG. 7 shows an example of a beam sweeping operation for asynchronization signal and system information in a downlink transmissionprocess. In FIG. 7, in the new RAT, a physical resource (or a physicalchannel) in which system information is transmitted using a broadcastingmethod is called a physical broadcast channel (xPBCH).

In this case, analog beams belonging to different antenna panels withinone symbol may be transmitted at the same time. A method of introducinga beam reference signal (BRS), that is, a reference signal transmittedby applying a single analog beam (corresponding to a specific antennapanel) as shown in FIG. 7 in order to measure a channel according to theanalog beam, is discussed.

The BRS may be defined with respect to a plurality of antenna ports, andeach antenna port of the BRS may correspond to a single analog beam.

In this case, unlike in the BRS, a synchronization signal or an xPBCHmay be transmitted by applying all of analog beams within an analog beamgroup so that signals transmitted by specific UEs are well received.

RRM Measurement

In the LTE system, RRM operations, including Power control, Scheduling,Cell search, Cell reselection, Handover, Radio link or Connectionmonitoring, Connection establish/re-establish, are supported.

In this case, a serving cell may request RRM measurement information,that is, a measured value for performing an RRM operation, from a UE.

For example, a UE may measure information, such as cell searchinformation, reference signal received power (RSRP) or reference signalreceived quality (RSRQ) for each cell, and may report it to a BS.

Specifically, in the LTE system, a UE receives “measConfig” from aserving cell through a higher layer signal for RRM measurement. The UEmeasures RSRP or RSRQ based on “measConfig.”

The definition of RSRP, RSRQ and RSSI is as follows.

-   -   RSRP: RSRP may be defined as a linear average for a power        contribution [W] of a resource element that delivers a        cell-specific reference signal within a considered measurement        frequency bandwidth. A cell-specific reference signal R0 may be        used for an RSRP determination. If a UE can reliably detect that        R1 is available, the UE may add R1 to R0 and determine RSRP        using R1.

A reference point of RSRP may be the antenna connector of a UE.

If receiver diversity is used by a UE, a reported value should not belower than corresponding RSRP of a specific individual diversity branch.

-   -   RSRQ: a reference signal reception quality (RSRQ) is defined as        a ratio N×RSRP/(E-UTRA carrier RSSI). N is the number of RBs of        an E-UTRA carrier RSSI measurement bandwidth. The measurement of        the numerator and denominator needs to be performed through the        same resource block set.

An E-UTRA carrier received signal strength indicator (RSSI) is receivedby a UE through a block from all of sources, including N resourceneighboring channel interference and thermal noise, in a linear averageof total received power [W] measured only in an OFDM symbol including areference symbol for the antenna port 0 and a measurement bandwidth.

If higher layer signaling indicates a specific subframe for performingRSRQ measurement, an RSSI is measured with respect to all of OFDMsymbols within the indicated subframe.

A reference point for RSRQ must be the antenna connector of a UE. Ifreceiver diversity is used by the UE, a reported value should not belower than corresponding RSRQ of a specific individual diversity branch.

RSSI: an RSSI means received wideband power, including thermal noise andnoise occurring in a received within a bandwidth defined by a receiverpulse shaping filter.

A reference point for the measurement of an RSSI must be the antennaconnector of a UE. If receiver diversity is used by the UE, a reportedvalue should not be lower than a corresponding UTRA carrier RSSI of aspecific individual reception antenna branch.

A UE operating in the LTE system according to the above definition maybe allowed to measure RSRP in a bandwidth corresponding to one of 6, 15,25, 50, 75 and 100 resource blocks (RBs) through an allowed measurementbandwidth-related information element (IE) transmitted in the systeminformation block type 3 (SIB3) in the case of intra-frequencymeasurement and through an allowed measurement bandwidth transmitted inthe SIB5 in the case of inter-frequency measurement.

Alternatively, if the above IE is not present, measurement may beperformed in a full frequency band of a downlink (DL) system by default.In this case, when the UE receives an allowed measurement bandwidth, theUE may consider a corresponding value to be a maximum measurementbandwidth and freely measure a value of RSRP within the correspondingvalue.

In this case, when a serving cell transmits an IE defined as a WB-RSRQand sets an allowed measurement bandwidth as 50 RBs or more, the UEshould calculate an RSRP value of a total allowed measurement bandwidth.Meanwhile, measurement may be performed in the frequency band of thereceiver of the UE according to the definition of an RSSI bandwidth withrespect to the RSSI.

FIG. 8 is a diagram showing an example of an antenna array to which amethod proposed in this specification may be applied.

In FIG. 8, a generalized panel antenna array may include Mg panels andNg panels in the horizontal domain and vertical domain, respectively.

In this case, one panel includes M columns and N rows. In FIG. 8, anX-pol antenna is assumed. Accordingly, a total number of antennaelements may include the number of 2*M*N*Mg*Ng.

Hereinafter, an LTE uplink (UL) codebook is described with reference toTable 4 to Table 8.

In Table 4 to Table 8, ν=1 means that the number of layers is 1.

Table 4 shows an example of a codebook for transmission on antenna ports{20,21}

TABLE 4 Codebook Number of layers index υ = 1 υ = 2 0$\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\1\end{bmatrix}$ $\frac{1}{\sqrt{2}}\begin{bmatrix}1 & 0 \\0 & 1\end{bmatrix}$ 1 $\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\{- 1}\end{bmatrix}$ — 2 $\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\j\end{bmatrix}$ — 3 $\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\{- j}\end{bmatrix}$ — 4 $\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\0\end{bmatrix}$ — 5 $\frac{1}{\sqrt{2}}\begin{bmatrix}0 \\1\end{bmatrix}$ —

Table 5 shows an example of a codebook for transmission on antenna ports{40,41,42,43} having ν=1.

TABLE 5 Codebook index Number of layers υ = 1  0-7 $\frac{1}{2}\begin{bmatrix}1 \\1 \\1 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\j \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\{- 1} \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\{- j} \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\1 \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\j \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\{- 1} \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\{- j} \\{- 1}\end{bmatrix}$  8-15 $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\j \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\{- 1} \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\{- j} \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\1 \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\j \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\{- j} \\{- 1} \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\{- j} \\1\end{bmatrix}$ 16-23 $\frac{1}{2}\begin{bmatrix}1 \\0 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\{- 1} \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\j \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\{- j} \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\{- j}\end{bmatrix}$

Table 6 shows an example of a codebook for transmission on antenna ports{40,41,42,43} having ν=2.

TABLE 6 Codebook index Number of layers υ = 2  0-3 $\frac{1}{2}\begin{bmatrix}1 & 0 \\1 & 0 \\0 & 1 \\0 & {- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 \\1 & 0 \\0 & 1 \\0 & j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 \\{- j} & 0 \\0 & 1 \\0 & 1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 \\{- j} & 0 \\0 & 1 \\0 & {- 1}\end{bmatrix}$  4-7  $\frac{1}{2}\begin{bmatrix}1 & 0 \\{- 1} & 0 \\0 & 1 \\0 & {- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 \\{- 1} & 0 \\0 & 1 \\0 & j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 \\j & 0 \\0 & 1 \\0 & 1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 \\j & 0 \\0 & 1 \\0 & {- 1}\end{bmatrix}$  8-11 $\frac{1}{2}\begin{bmatrix}1 & 0 \\0 & 1 \\1 & 0 \\0 & 1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 \\0 & 1 \\1 & 0 \\0 & {- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 \\0 & 1 \\{- 1} & 0 \\0 & 1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 \\0 & 0 \\{- 1} & 0 \\0 & {- 1}\end{bmatrix}$ 12-15 $\frac{1}{2}\begin{bmatrix}1 & 0 \\0 & 1 \\0 & 1 \\1 & 0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 \\0 & 1 \\0 & {- 1} \\1 & 0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 \\0 & 1 \\0 & 1 \\{- 1} & 0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 \\0 & 1 \\0 & {- 1} \\{- 1} & 0\end{bmatrix}$

Table 7 shows an example of a codebook for transmission on antenna ports{40,41,42,43} having ν=3.

TABLE 7 Codebook index Number of layers υ = 3 0-3 $\frac{1}{2}\begin{bmatrix}1 & 0 & 0 \\1 & 0 & 0 \\0 & 1 & 0 \\0 & 0 & 1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 & 0 \\{- 1} & 0 & 0 \\0 & 1 & 0 \\0 & 0 & 1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 & 0 \\0 & 1 & 0 \\1 & 0 & 0 \\0 & 0 & 1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 & 0 \\0 & 1 & 0 \\{- 1} & 0 & 0 \\0 & 0 & 1\end{bmatrix}$ 4-7  $\frac{1}{2}\begin{bmatrix}1 & 0 & 0 \\0 & 1 & 0 \\0 & 0 & 1 \\1 & 0 & 0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 & 0 & 0 \\0 & 1 & 0 \\0 & 0 & 1 \\{- 1} & 0 & 0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 & 1 & 0 \\1 & 0 & 0 \\1 & 0 & 0 \\0 & 0 & 1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 & 1 & 0 \\1 & 0 & 0 \\{- 1} & 0 & 0 \\0 & 0 & 1\end{bmatrix}$ 8-11 $\frac{1}{2}\begin{bmatrix}0 & 1 & 0 \\1 & 0 & 0 \\0 & 0 & 1 \\1 & 0 & 0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 & 1 & 0 \\1 & 0 & 0 \\0 & 0 & 1 \\{- 1} & 0 & 0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 & 1 & 0 \\0 & 0 & 1 \\1 & 0 & 0 \\1 & 0 & 0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 & 1 & 0 \\0 & 0 & 1 \\1 & 0 & 0 \\{- 1} & 0 & 0\end{bmatrix}$

Table 8 shows an example of a codebook for transmission on antenna ports{40,41,42,43} having ν=4.

TABLE 8 Codebook Number of index layers υ = 4 0$\frac{1}{2}\begin{bmatrix}1 & 0 & 0 & 0 \\0 & 1 & 0 & 0 \\0 & 0 & 1 & 0 \\0 & 0 & 0 & 1\end{bmatrix}$

NR codebook-related contents are described in brief, and a codebookconfiguration method proposed in this specification is described indetail.

If only a wideband transmit precoding matrix indicator (TPMI) or atransmitted precoding matrix indicator is used for DFT-s-OFDM, a rank 1precoder is used in the following table (Table 9) with respect to 2Tx.

In this case, 2Tx may be construed as having the same meaning astransmission through two antenna ports.

A “codebook index” used in the following tables means a “TPMI index.”

The TPMI is used to indicate a transmission precoder to be applied on aspecific antenna port and may be represented as a precoding matrix or acodeword.

TABLE 9 Codebook Number of layers index υ = 1 υ = 2 0$\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\1\end{bmatrix}$ $\frac{1}{\sqrt{2}}\begin{bmatrix}1 & 1 \\1 & {- 1}\end{bmatrix}$ 1 $\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\{- 1}\end{bmatrix}$ $\frac{1}{\sqrt{2}}\begin{bmatrix}1 & 1 \\j & {- j}\end{bmatrix}$ 2 $\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\j\end{bmatrix}$ $\frac{1}{\sqrt{2}}\begin{bmatrix}1 & 0 \\0 & 1\end{bmatrix}$ 3 $\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\{- j}\end{bmatrix}$ — 4 $\frac{1}{\sqrt{2}}\begin{bmatrix}1 \\0\end{bmatrix}$ — 5 $\frac{1}{\sqrt{2}}\begin{bmatrix}0 \\1\end{bmatrix}$ —

In Rel-15, single stage downlink control information (DCI) having a sizesemi-statically set to deliver a TPMI, an SRS resource indicator (SRI)or a transmit (or transmitted) rank indicator (TM) is used with respectto 2Tx.

A total DCI size in which a TPMI, TRI and SRI are combined is notdifferent depending on PUSCH resource allocation for single stage DCI.

A UE capability to identify whether an UL MIMO-capable UE can supportcoherent transmission through its own transmit chain is specified.

Hereinafter, if discrete Fourier transform spread orthogonal frequencydivision multiplexing (DFT-s-OFDM) is used in an environment, such as NRproposed in this specification, a method of designing a codebook aredescribed through various embodiments.

An antenna used in this specification indicates an antenna port or anantenna element, and is represented as an “antenna port”, forconvenience of description.

First Embodiment

The first embodiment relates to a method of configuring a 4Tx codebookof DFT-s-OFDM according to Table 10 to Table 19 or a combinationthereof.

In the case of an LTE Uplink codebook, the TPMIs of all of ranks areconfigured to be joint-encoded, thus reducing overhead of DCI. Rank 1includes 24 states.

In the case of NR, a performance gain can be achieved by increasingcodebook granularity using all of 32 states because DFT-s-OFDM supportsonly rank 1.

Furthermore, the remaining 8 states may include a combination of 1-portselection, 2-port selection and/or 3-port selection codebooks, and Table10 to Table 19 show examples thereof.

Table 10 shows an example of a 4Tx DFT-s-OFDM codebook for rank 1.

TABLE 10 Codebook index Number of layers υ = 1  0-7 $\frac{1}{2}\begin{bmatrix}1 \\1 \\1 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\j \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\{- 1} \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\{- j} \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\1 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\j \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\{- 1} \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\{- j} \\{- 1}\end{bmatrix}$  8-15 $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\j \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\{- 1} \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\{- j} \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\1 \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\j \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\{- 1} \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\{- j} \\1\end{bmatrix}$ 16-23 $\frac{1}{2}\begin{bmatrix}1 \\0 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\{- 1} \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\j \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\{- j} \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\{- j}\end{bmatrix}$ 24-34 $\frac{1}{2}\begin{bmatrix}1 \\1 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\{- j}\end{bmatrix}$

Thereafter, in the case of Table 11 to Table 19, For convenience ofexpression, 0-23 indices are considered to use the 0-23 indices of Table10 without any change, a codebook (or a codeword or precoding matrix)corresponding to the 24-31 indices complies with the proposal of eachtable below.

Table 11 shows another example of a 4Tx DFT-s-OFDM codebook for rank 1.

TABLE 11 Codebook index Number of of layers ^(ν=1) 24-31$\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\{- 1} \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\j \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\{- j} \\0\end{bmatrix}$

Table 12 and Table 13 show examples including combinations of Table 10and Table 11.

Table 12 is an example in which the degree of freedom of an antennaselection combination is abandoned (when two antennas of Tx antenna Nos.0, 1, 2, and 3 are “On”, a combination of the Tx antenna Nos. 2 and 3and a combination of the Tx antenna Nos. 1 and 2 are abandoned) and thecodebook granularity of a given antenna port combination has beenextended.

That is, in Table 12, a QPSK co-phase of 1, −1, j, −j is considered.

Unlike Table 12, Table 13 is an example in which a specific number(e.g., two, {1, −1} or {1, j }) is used as the co-phase of a givenantenna port combination and a combination of antenna ports that become“On” has been increased.

Table 12 shows another example of a 4Tx DFT-s-OFDM codebook for rank 1.

TABLE 12 Codebook index Number of layers υ = 1 24-31$\frac{1}{2}\begin{bmatrix}1 \\1 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\{- j}\end{bmatrix}$

Table 13 shows another example of a 4Tx DFT-s-OFDM codebook for rank 1.

TABLE 13 Codebook index Number of layers υ = 1 24-31$\frac{1}{2}\begin{bmatrix}1 \\1 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\{- 1} \\0\end{bmatrix}$

In the antenna port “On” and/or “Off” codebook of Table 10 to Table 13,a case where two antenna ports are selected in 4Tx has been considered.However, Table 14 shows an example in which 1 and 3 antenna ports areselected from 4Tx.

As described above, an advantage of an antenna selection codebook isthat if performance deterioration occurs due to transmission delaybetween antenna ports upon wideband TPMI transmission (by a basestation), the base station (e.g., gNB) can indicate that which antennaports can be transmitted at the same time (UL coherent transmissionbetween antenna ports) through a codebook.

Table 14 shows another example of a 4Tx DFT-s-OFDM codebook for rank 1.

TABLE 14 Codebook index Number of layers υ = 1 24-31$\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\1 \\1\end{bmatrix}$

Table 15 shows another example of a 4Tx DFT-s-OFDM codebook for rank 1.

TABLE 15 Codebook index Number of layer υ = 1 24-31$\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\{- 1} \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\j \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\{- j} \\0\end{bmatrix}$

Table 14 and Table 15 have a great effect in the battery saving of a UEin the case of 1-port selection, but performance deterioration may beexpected because an antenna array gain is rarely obtained.

Accordingly, a method of further allocating the state for 1-portselection to the state for 3-port selection may be taken intoconsideration, and Table 16 and Table 17 show examples thereof.

That is, as in Table 16 and Table 17, to provide the degree of freedomto port selection has an advantage in that it can increase flexibilityin the Tx antenna design of a UE.

Table 16 shows another example of a 4Tx DFT-s-OFDM codebook for rank 1.

TABLE 16 Codebook index Number of layers υ = 1 24-31$\frac{1}{2}\begin{bmatrix}1 \\1 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\{- 1} \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\0 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\1 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\1 \\{- 1}\end{bmatrix}$

Performance of a codebook may be determined according to a method ofselecting a codeword that maximizes the Euclidean Distance betweencodewords configuring a codebook.

In this case, the Euclidean Distance may be defined like Equation 2.

Dist(a, b)=∥a−b∥  [Equation 2]

In this case, “a” and “b” are vectors having the same length.

If the metric (Equation 2) is used, a codeword to maximize the Euclideandistance may be codebook indices 24-27 of Table 17.

In this case, Table 18 and Table 19 may be taken into considerationbecause only a specific first antenna port is not used.

Table 17 shows another example of a 4Tx DFT-s-OFDM codebook for rank 1.

TABLE 17 Codebook index Number of layers υ = 1 24-31$\frac{1}{2}\begin{bmatrix}0 \\1 \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\{- 1} \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\j \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\{- j} \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\0 \\1\end{bmatrix}$

Table 18 shows another example of a 4Tx DFT-s-OFDM codebook for rank 1.

TABLE 18 Codebook index Number of layers υ = 1 24-31$\frac{1}{2}\begin{bmatrix}0 \\1 \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\{- 1} \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\j \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\{- j} \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\0 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\0 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\0 \\{- j}\end{bmatrix}$

Table 19 shows another example of a 4Tx DFT-s-OFDM codebook for rank 1.

TABLE 19 Codebook index Number of layers υ = 1 24-31$\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\{- 1} \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\j \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\{- j} \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\0 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\0 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\0 \\{- j}\end{bmatrix}$

Second Embodiment

The second embodiment relates to a method of configuring an x-bit (e.g.,x=6) table having a greater bit-width in order to include the codebookof the first embodiment in the case of a 4Tx codebook of DFT-s-OFDM.

An LTE uplink 4Tx codebook requires 6 bits because a transmit precodingindicator (TPI) and a transmit rank indicator (TRI) are jointlyindicated.

The first embodiment has proposed a configuration method using 5 bits inorder to reduce signaling overhead of 6 bits.

The second embodiment proposes a method of configuring granularity forrank 1 more abundantly, having the same bit-width as the LTE system.

In Table 20, 16-31 indices have been added in order to make moreabundant granularity when all of 4Txs are used.

That is, the co-phases of the fixed 0, 1 and 2 Txs have used QPSK and aco-phase having only one granularity corresponding to the No. 3 Tx hasbeen used. However, the 16-31 indices of Table 20 are a case wheregranularity of a co-phase corresponding to the No. 3 Tx has beenincreased to “2.”

Thereafter, the 32-63 indices of Table 20 correspond to a codeword forantenna port selection.

Table 20 shows another example of a 4Tx DFT-s-OFDM codebook for rank 1.

TABLE 20 Codebook index Number of layers υ = 1 0-7$\frac{1}{2}\begin{bmatrix}1 \\1 \\1 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\j \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\{- 1} \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\{- j} \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\1 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\j \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\{- 1} \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\{- j} \\{- 1}\end{bmatrix}$  8-15 $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\j \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\{- 1} \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\{- j} \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\1 \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\j \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\{- 1} \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\{- j} \\1\end{bmatrix}$ 16-23 $\frac{1}{2}\begin{bmatrix}1 \\1 \\1 \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\j \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\{- 1} \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\{- j} \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\1 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\j \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\{- 1} \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\{- j} \\{- j}\end{bmatrix}$ 24-31 $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\1 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\j \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\{- 1} \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\{- j} \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\j \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\{- 1} \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\{- j} \\j\end{bmatrix}$ 32-39 $\frac{1}{2}\begin{bmatrix}1 \\0 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\{- 1} \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\j \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\{- j} \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\{- j}\end{bmatrix}$ 40-47 $\frac{1}{2}\begin{bmatrix}1 \\1 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- 1} \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\j \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\{- j} \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\{- j}\end{bmatrix}$ 48-55 $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\{- 1}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\j\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\{- j}\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\{- 1} \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\j \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\{- j} \\0\end{bmatrix}$ 56-63 $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\1 \\1\end{bmatrix}$

In the codebook, in the case of 3-port (indices 60-63), the codewords ofTable 16 to Table 19 may be used.

Third Embodiment

In the third embodiment, a codebook may be indicated by a TPMI 1 used toindicate antenna port selection (4CL, L=1,2,3,4) and a port combiningcodebook TPMI 2 of a Tx antenna port selected by the TPMI 1.

The third embodiment may be applied to select an (antenna) panel and toselect or determine a codebook for an antenna port in the selectedpanel.

In the third embodiment, the TPMI 1 and TPMI 2 may be indicated bydifferent fields within DCI, and the size of the TPMI 2 may havedependency on the TPMI 1.

The third embodiment has an advantage in that more efficient signalingis possible because a bit-width for total TPMI indication varies, butthe complexity of a UE for decoding a DCI size may rise because the DCIsize varies.

The configuration of the TPMI 1 is represented as an X-bitmap (e.g.,X=4) in the case of an X-port, for example, and may indicate an antennaport(s) to which a port combining codebook is applied with respect to aUE.

For example, if a 4-bitmap “1010” is indicated, Nos. 0 and ports may beconsidered to be “ON.”

Furthermore, a UE does not expect that the bitmap of “0000” (i.e., allof antenna ports are OFF) is indicated.

Alternatively, the bitmap may be indicated as follows using a table (ora subset thereof, for example, if only the 1, 2, 4 antenna selection isallowed).

Table 21 shows an example of a 4Tx TPMI 1 configuration.

TABLE 21 Codebook index Number of layers v = 1 0-7$\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\0 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\1 \\0\end{bmatrix}$ 8-15 $\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\1 \\0\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\0 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\0 \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}0 \\1 \\1 \\1\end{bmatrix}$ $\frac{1}{2}\begin{bmatrix}1 \\1 \\1 \\1\end{bmatrix}$ —

Furthermore, in the case of 4Tx, an example of a TPMI 2 configuration isas follows.

Y is the bit width of granularity of a co-phase, and indicates QPSK (1,−1, j, −j) in the case of Y=2 and may be configured through higher layersignaling.

−1-port selection, 0-bit TPMI2

−2-port selection, Y-bit TPMI2

$\begin{matrix}{{{{TPMI}\; 2} = \begin{bmatrix}1 \\{\exp ( \frac{j\; 2\; \pi \; n}{2^{Y}} )}\end{bmatrix}},{n = 0},1,\; {.\;.\;.}\mspace{14mu},{2^{Y} - 1}} & \lbrack {{Equation}\mspace{14mu} 3} \rbrack\end{matrix}$

For example, Y=2 and an index 8 is indicated in the TPMI1. In the caseof n=1 of the TPMI2, a UE may recognize that the final TPMI has

${\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\j\end{bmatrix}}.$

−3-port selection, 2Y-bit TPMI2

$\begin{matrix}{{{{TPMI}\; 2} = \begin{bmatrix}1 \\{\exp ( \frac{j\; 2\; \pi \; n_{1}}{2^{Y}} )} \\{\exp ( \frac{j\; 2\; \pi \; n_{2}}{2^{Y}} )}\end{bmatrix}},{n_{i} = 0},1,\; {.\;.\;.}\mspace{14mu},{2^{Y} - 1},{i = 1},2} & \lbrack {{Equation}\mspace{14mu} 4} \rbrack\end{matrix}$

For example, Y=2 and an index 10 is indicated in the TPMI1. In the caseof n1=1 of

the TPMI2 and n2=3, a UE may recognize that the final TPMI includes

${\frac{1}{2}\begin{bmatrix}1 \\j \\{- j} \\0\end{bmatrix}}.$

−4-port selection, 3Y-bit TPMI2

$\begin{matrix}{{{{TPMI}\; 2} = \begin{bmatrix}1 \\{\exp ( \frac{j\; 2\; \pi \; n_{1}}{2^{Y}} )} \\{\exp ( \frac{j\; 2\; \pi \; n_{2}}{2^{Y}} )} \\{\exp ( \frac{j\; 2\; \pi \; n_{3}}{2^{Y}} )}\end{bmatrix}},{n_{i} = 0},1,\; {.\;.\;.}\mspace{14mu},{2^{Y} - 1},{i = 1},2,3} & \lbrack {{Equation}\mspace{14mu} 5} \rbrack\end{matrix}$

In the above example, if TPMI1+TPMI2 are independently signaled, thereis signaling overhead of 10 bits as a maximum TPMI1=4 bits and TPMI2=6bits (assuming Y=2).

In order to reduce overhead of the TPMI2 of the third embodiment or toobviate bit-width dependency on the TPMI1, the TPMI2 may be previouslyagreed as a codebook having a subset of the aforementioned methods.

For example, the TPMI2 may be fixed to 4 bits regardless of the TPMI1.

In this case, in the case of the 1-port and 2-port having remainingstates, a UE recognizes them as reserved states and does not expectindication for the states.

Furthermore, in the case of 4-port selection having an insufficientstate, the 4-port selection may be sub-sampled as 4-bit according to thespecific agreement, and an example thereof may be a codebookcorresponding to the Nos. 0 to 15 indices of Table 20.

The aforementioned methods have been described in connection withDFT-s-OFDM, but may also be applied to CP-OFDM.

In this case, the TPMI2 may be joint-encoded into TPMI2+TRI andsignaled.

Fourth Embodiment

In the fourth embodiment, in the case of antenna selection codewordbelonging to the above proposed codebooks and having an entry of “0”,specific values (UE-reported values and/or pre-defined values) of ascaling factor may be set through higher layer signaling depending onthe UE capability.

The higher layer signaling may be RRC, a medium access control (MAC)control element (CE) or DCI, for example.

For example, in the case of rank 1, in the case of an expression as 4Txcodebook,

${\frac{1}{\rho}v},$

the value of ρ may be indicated as ρ∈{2√{square root over (6)},2√{squareroot over (2)},4)}.

In this case, ρ is a scaling factor, and ν indicates a length-L (L=4)vector.

As the value of σ increases, the dynamic range of the power amplifier ofa UE is increased, and there is a good possibility that the UE is ahigh-end UE.

The UE may report a possible value of the σ values to a base station bytaking into consideration the dynamic range of the power amplifier ofits own RF-chain.

In this case, the base station may set a specific value of the σ valuesthrough a higher layer with respect to the UE or may previously define aspecific value (e.g., max value) of values reported by the UE.

In general, the value of σ is semi-statically set depending on thecapability of a UE.

However, in the case of UL heavy traffic, if the value of σ is higher,interference may be caused. Accordingly, the value of σ may bedynamically indicated using DCI in order to control the value of σ.

Alternatively, a UE may report a change request or change indicator fora σ value to a base station by considering its own battery.

Likewise, the fourth embodiment may be identically applied to CP-OFDM,and all of the embodiments may be identically applied to CP-OFDM.

FIG. 9 is a flowchart showing an example of an operating method of a UEperforming codebook-based uplink transmission, which is proposed in thisspecification.

First, the UE receives downlink control information (DCI), including afirst transmit precoding matrix indicator (TPMI), from a base station(S910).

In this case, the first TPMI may be a wideband TPMI.

Furthermore, the UE determines a codebook subset related to thetransmission of an uplink signal based on the first TPMI (S920).

In this case, the codebook subset is included in a codebook for rank 1using four antenna ports.

Furthermore, the codebook subset may include at least one codeword forselecting one antenna port. For detailed contents, reference is made toTable 14 and Table 15.

Specifically, the at least one codeword may be configured as

${\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\0\end{bmatrix}},{\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\0\end{bmatrix}},{{\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\0\end{bmatrix}}\mspace{14mu} {and}\mspace{14mu} {{\frac{1}{2}\begin{bmatrix}0 \\0 \\0 \\1\end{bmatrix}}.}}$

That is, the at least one codeword may be configured as codewords (orprecoding matrices or precoders or codebook subsets) corresponding to a4 codebook index.

That is, the 1-port selection proposed in this specification may beconfigured as using the 4 states of a codebook.

Furthermore, the codebook for rank 1 using the one antenna ports may becodebook using discrete Fourier transform spread orthogonal frequencydivision multiplexing (DFT-s-OFDM).

As shown in Table 14 and Table 15, the 1-port selection has an advantagein the battery saving of a UE because only one antenna port is “ON.”

Furthermore, the UE transmits an uplink signal to the base station usingthe determined codebook subset (S930).

Additionally, the DCI may further include a second TPMI related to theport combining of an antenna port selected based on the first TPMI.

The size of the second TPMI may be determined based on the size of thefirst TPMI.

In this case, the first TPMI may be expressed as an X-bitmap.

The X value indicates the number of antenna ports. For example, if thenumber of antenna ports is 4, the X value is 4.

Furthermore, the second TPMI may be configured based on Equations 3 to5.

Additionally, the UE may perform scaling on a codeword whose normalizeis not “1” depending on its capability.

That is, the UE receives signaling, including a scaling element to beapplied to the at least one codeword, from the base station, and mayperform scaling on the aforementioned codeword by applying the powerscaling factor to the at least one codeword.

Furthermore, the power scaling factor may be configured by taking intoconsideration the capability of the UE.

General apparatus to which the present invention may be applied

FIG. 10 illustrates a block diagram of a wireless communicationapparatus to which the methods proposed in this specification may beapplied.

Referring to FIG. 10, the wireless communication system includes an eNB1010 and multiple UEs 1020 disposed in the eNB area.

The eNB and the UE may be represented as respective wireless devices.

The eNB includes a processor 1011, memory 1012 and a radio frequency(RF) module 1013. The processor 1011 implements the functions, processesand/or methods proposed in FIGS. 1 to 9. The layers of a radio interfaceprotocol may be implemented by the processor. The memory is connected tothe processor and stores a variety of types of information for drivingthe processor. The RF module is connected to the processor and transmitsand/or receives radio signals.

The UE includes a processor 1021, memory 1022 and an RF module 1023.

The processor implements the functions, processes and/or methodsproposed in FIGS. 1 to 9. The layers of a radio interface protocol maybe implemented by the processor. The memory is connected to theprocessor and stores a variety of types of information for driving theprocessor. The RF module is connected to the processor and transmitsand/or receives radio signals.

The memory 1012, 1022 may be positioned inside or outside the processor1011, 1021 and may be connected to the processor by various well-knownmeans.

Furthermore, the eNB and/or the UE may have a single antenna or multipleantennas.

The antenna 1014, 1024 functions to transmit and receive radio signals.

FIG. 11 illustrates a block diagram of a communication apparatusaccording to an embodiment of the present invention.

Specifically, FIG. 11 is a detail diagram of the UE of FIG. 10.

Referring to FIG. 11, the UE may include a processor (or digital signalprocessor (DSP) 1110, an RF module (or the RF unit) 1135, a powermanagement module 1105, an antenna 1140, a battery 1155, a display 1115,a keypad 1120, memory 1130, a subscriber identification module (SIM)card 1125 (this element is optional), a speaker 1145 and a microphone1150. The UE may further include a single antenna or multiple antennas.

The processor 1110 implements the functions, processes and/or methodsproposed in FIGS. 1 to 9. The layers of a radio interface protocol maybe implemented by the processor.

The memory 1130 is connected to the processor and stores informationrelated to an operation of the processor. The memory may be positionedinside or outside the processor and may be connected to the processor byvarious well-known means.

A user inputs command information, such as a telephone number, bypressing (or touching) a button of the keypad 1120 or through voiceactivation using the microphone 1150, for example. The processorreceives such command information and performs processing so that aproper function, such as making a phone call to the telephone number, isperformed. Operational data may be extracted from the SIM card 1125 orthe memory. Furthermore, the processor may recognize and display commandinformation or driving information on the display 1115, for conveniencesake.

The RF module 1135 is connected to the processor and transmits and/orreceives RF signals. The processor delivers command information to theRF module so that the RF module transmits a radio signal that formsvoice communication data, for example, in order to initiatecommunication. The RF module includes a receiver and a transmitter inorder to receive and transmit radio signals. The antenna 1140 functionsto transmit and receive radio signals. When a radio signal is received,the RF module delivers the radio signal so that it is processed by theprocessor, and may convert the signal into a baseband. The processedsignal may be converted into audible or readable information outputthrough the speaker 1145.

FIG. 12 is a diagram showing an example of the RF module of the wirelesscommunication apparatus to which a method proposed in this specificationmay be applied.

Specifically, FIG. 12 shows an example of an RF module that may beimplemented in a frequency division duplex (FDD) system.

First, in a transmission path, the processor described in FIGS. 10 and11 processes data to be transmitted and provides an analog output signalto a transmitter 1210.

In the transmitter 1210, the analog output signal is filtered by a lowpass filter (LPF) 1211 in order to remove images caused bydigital-to-analog conversion (ADC). The signal is up-converted from abaseband to an RF by a mixer 1212 and is amplified by a variable gainamplifier (VGA) 1213. The amplified signal is filtered by a filter 1214,additionally amplified by a power amplifier (PA) 1215, routed by aduplexer(s) 1250/antenna switch(es) 1260, and transmitted through anantenna 1270.

Furthermore, in a reception path, the antenna 1270 receives signals fromthe outside and provides the received signals. The signals are routed bythe antenna switch(es) 1260/duplexers 1250 and provided to a receiver1220.

In the receiver 1220, the received signals are amplified by a low noiseamplifier (LNA) 1223, filtered by a band pass filter 1224, anddown-converted from the RF to the baseband by a mixer 1225.

The down-converted signal is filtered by a low pass filter (LPF) 1226and amplified by a VGA 1227, thereby obtaining the analog input signal.The analog input signal is provided to the processor described in FIGS.10 and 11.

Furthermore, a local oscillator (LO) 1240 generates transmission andreception LO signals and provides them to the mixer 1212 and the mixer1225, respectively.

Furthermore, a phase locked loop (PLL) 1230 receives control informationfrom the processor in order to generate transmission and reception LOsignals in proper frequencies, and provides control signals to the localoscillator 1240.

Furthermore, the circuits shown in FIG. 12 may be arrayed differentlyfrom the configuration shown in FIG. 12.

FIG. 13 is a diagram showing another example of the RF module of thewireless communication apparatus to which a method proposed in thisspecification may be applied.

Specifically, FIG. 13 shows an example of an RF module that may beimplemented in a time division duplex (TDD) system.

The transmitter 1310 and receiver 1320 of the RF module in the TDDsystem have the same structure as the transmitter and receiver of the RFmodule in the FDD system.

Hereinafter, only a different structure between the RF module of the TDDsystem and the RF module of the FDD system is described. Reference ismade to the description of FIG. 12 for the same structure.

A signal amplified by the power amplifier (PA) 1315 of the transmitteris routed through a band select switch 1350, a band pass filter (BPF)1360 and an antenna switch(es) 1370 and is transmitted through anantenna 1380.

Furthermore, in a reception path, the antenna 1380 receives signals fromthe outside and provides the received signals. The signals are routedthrough the antenna switch(es) 1370, the band pass filter 1360 and theband select switch 1350 and are provided to the receiver 1320.

In the aforementioned embodiments, the elements and characteristics ofthe present invention have been combined in specific forms. Each of theelements or characteristics may be considered to be optional unlessotherwise described explicitly. Each of the elements or characteristicsmay be implemented in a form to be not combined with other elements orcharacteristics. Furthermore, some of the elements and/or thecharacteristics may be combined to form an embodiment of the presentinvention. The sequence of the operations described in the embodimentsof the present invention may be changed. Some of the elements orcharacteristics of an embodiment may be included in another embodimentor may be replaced with corresponding elements or characteristics ofanother embodiment. It is evident that an embodiment may be constructedby combining claims not having an explicit citation relation in theclaims or may be included as a new claim by amendments after filing anapplication.

The embodiment according to the present invention may be implemented byvarious means, for example, hardware, firmware, software or acombination of them. In the case of an implementation by hardware, theembodiment of the present invention may be implemented using one or moreapplication-specific integrated circuits (ASICs), digital signalprocessors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), field programmable gate arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In the case of an implementation by firmware or software, the embodimentof the present invention may be implemented in the form of a module,procedure or function for performing the aforementioned functions oroperations. Software code may be stored in the memory and driven by theprocessor. The memory may be located inside or outside the processor andmay exchange data with the processor through a variety of known means.

The method of transmitting an uplink signal in a wireless communicationsystem according to the present invention has been described based on anexample in which it is applied to the 3GPP LTE/LTE-A system and the 5Gsystem (new RAT system), but may be applied to various wirelesscommunication systems in addition to the 3GPP LTE/LTE-A system and the5G system.

This specification has an advantage in that it can improve flexibilityin designing a transmission antenna in a UE by increasing the degree offreedom for antenna port selection through a codebook configuration for1-port selection.

Effects which may be obtained by the present invention are not limitedto the aforementioned effects, and various other effects may beevidently understood by those skilled in the art to which the presentinvention pertains from the following description.

It is evident to those skilled in the art that the present invention maybe materialized in other specific forms without departing from theessential characteristics of the present invention. Accordingly, thedetailed description should not be construed as being limitative fromall aspects, but should be construed as being illustrative. The scope ofthe present invention should be determined by reasonable analysis of theattached claims, and all changes within the equivalent range of thepresent invention are included in the scope of the present invention.

What is claimed is:
 1. A method of transmitting, by a user equipment(UE), a uplink signal based on a codebook in a wireless communicationsystem, the method comprising: receiving, from a base station, downlinkcontrol information (DCI) including a first transmit precoding matrixindicator (TPMI); determining a codebook subset related to atransmission of the uplink signal based on the first TPMI; andtransmitting, to the base station, the uplink signal based on thedetermined codebook subset, wherein the codebook subset is included in acodebook for a rank 1 using four antenna ports, and wherein the codebooksubset includes at least one codeword for selecting one antenna port. 2.The method of claim 1, wherein the at least one codeword is${\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\0\end{bmatrix}},{\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\0\end{bmatrix}},{{\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\0\end{bmatrix}}\mspace{14mu} {and}\mspace{14mu} {{\frac{1}{2}\begin{bmatrix}0 \\0 \\0 \\1\end{bmatrix}}.}}$
 3. The method of claim 1, wherein the codebook for arank 1 using the one antenna ports includes a codebook based on discreteFourier transform spread orthogonal frequency division multiplexing(DFT-s-OFDM).
 4. The method of claim 1, wherein the DCI further includesa second TPMI related to port combining of an antenna port selectedbased on the first TPMI.
 5. The method of claim 4, wherein a size of thesecond TPMI is determined based on a size of the first TPMI.
 6. Themethod of claim 5, wherein: the first TPMI is represented as anX-bitmap, and a value of the X is a number of antenna ports.
 7. Themethod of claim 1, further comprising: receiving, from the base station,a signaling including a power scaling factor to be applied to the atleast one codeword; and applying the power scaling factor to the atleast one codeword.
 8. The method of claim 7, wherein the power scalingfactor is configured by considering a capability of the UE.
 9. Themethod of claim 1, wherein the first TPMI includes a wideband TPMI. 10.A user equipment (UE) transmitting a uplink signal based on a codebookin a wireless communication system, the UE comprising: a radio frequency(RF) module configured to transmit and receive radio signals; and aprocessor functionally connected to the RF module, wherein the processoris configured to: receive, from a base station, downlink controlinformation (DCI) including a first transmit precoding matrix indicator(TPMI), determine a codebook subset related to a transmission of theuplink signal based on the first TPMI, and transmit, to the basestation, the uplink signal based on the determined codebook subset,wherein the codebook subset is included in a codebook for a rank 1 usingfour antenna ports, and wherein the codebook subset includes at leastone codeword for selecting one antenna port.
 11. The UE of claim 10, theat least one codeword is ${\frac{1}{2}\begin{bmatrix}1 \\0 \\0 \\0\end{bmatrix}},{\frac{1}{2}\begin{bmatrix}0 \\1 \\0 \\0\end{bmatrix}},{{\frac{1}{2}\begin{bmatrix}0 \\0 \\1 \\0\end{bmatrix}}\mspace{14mu} {and}\mspace{14mu} {{\frac{1}{2}\begin{bmatrix}0 \\0 \\0 \\1\end{bmatrix}}.}}$
 12. The UE of claim 10, wherein the codebook for arank 1 using the one antenna ports includes a codebook based on discreteFourier transform spread orthogonal frequency division multiplexing(DFT-s-OFDM).
 13. The UE of claim 10, wherein the DCI further includes asecond TPMI related to port combining of an antenna port selected basedon the first TPMI.
 14. The UE of claim 10, wherein the first TPMIincludes a wideband TPMI.